switched up some pointers to shared, added some more rendering example

src/engine/engine.hpp

@@ -25,7 +25,7 @@ public:
     Engine(std::unique_ptr<Game> game, std::unique_ptr<Renderer> renderer,
            std::unique_ptr<InputProcessor> input_processor);
     void start_loop();
-    std::chrono::time_point<std::chrono::system_clock> render_fps(std::chrono::time_point<std::chrono::system_clock> end, std::chrono::time_point<std::chrono::system_clock> lastframe);
+
 
     virtual ~Engine();
 
@@ -33,6 +33,7 @@ private:
     std::unique_ptr<Game> game = nullptr;
     std::unique_ptr<Renderer> renderer = nullptr;
     std::unique_ptr<InputProcessor> input_processor = nullptr;
+    std::chrono::time_point<std::chrono::system_clock> render_fps(std::chrono::time_point<std::chrono::system_clock> end, std::chrono::time_point<std::chrono::system_clock> lastframe);
 };
 
 class MissingGameException : public std::exception {